1. Field of the Invention
This invention relates to a stereoscopic display by which a stereoscopic image can be observed without using special eye-glasses.
2. Description of the Prior Art
A stereoscopic display of double-lenticular type which uses two liquid crystal projectors and a double lenticular screen as a screen to realize stereoscopic image display without using special eye-glasses has been proposed. In the stereoscopic display of this type as shown in FIG. 15, one liquid crystal projector 100a displays an image for a left eye, and another liquid crystal projector 100b displays an image for a right eye. The images from the projectors are projected on a double lenticular screen 200 which is arranged in front of the projectors. The double lenticular screen 200 is constructed so that a diffusing plate 200b, which forms an image, is sandwiched by lenticular screens 200a and 200c. Images for left and right eyes become vertical stripe-shaped images 200bL and 200bR respectively by passing through the lenticular screen 200a, which is positioned on a light incident side (on the side of liquid crystal projectors 100a and 100b). And the vertical stripe-shaped images 200bL and 200bR are formed on the diffusing plate 200b. After that, these images are separated into the stripe-shaped image for a right eye and a left eye by passing through the lenticular screen 200c which is positioned on a light emitting side of the diffusing plate 200b (on the side of a viewer), then the image for a right eye is guided to a right eye (3R) of a viewer 300 and the image for a left eye is guided to a left eye (3L) of the viewer 300. The viewer, who observes these vertical stripe-shaped images for left and right eyes by the respective eyes, can observe a stereoscopic image without using special eye-glasses, due to the binocular parallax effect.
The stereoscopic display of this type provides a region in which an image for a right eye is visible and a region in which an image for a left eye is visible alternately at the optimum viewing distance from a screen 200 (xe2x80x9cDxe2x80x9d in the figure) as shown in FIG. 16. The xe2x80x9cRxe2x80x9d region indicated by an arrow is a region where an image for a right eye can be observed and the xe2x80x9cLxe2x80x9d region is a region where an image for a left eye where an image for a left eye can be observed. Accordingly, a viewer can observe a stereoscopic image when the right eye 3R of the viewer is in the xe2x80x9cRxe2x80x9d region and the left eye 3L is in the xe2x80x9cLxe2x80x9d region (the viewer is at the xe2x80x9cAxe2x80x9d position in the figure). When the right eye of the viewer is in the xe2x80x9cLxe2x80x9d region and the left eye is in the xe2x80x9cRxe2x80x9d region (the viewer is at the xe2x80x9cBxe2x80x9d position in the figure), a viewer observes a pseudo-stereoscopic image and can not observe a stereoscopic image.
The conventional methods which can prevent a pseudo-stereoscopic image caused by a shift of the viewer""s head include the following one. As illustrated in FIGS. 17 and 18, a sensor 210 which detects a head position of a viewer 300 detects a head position of the viewer 300. When the sensor determines the viewer is at a pseudo-stereoscopic viewing position, images from the two projectors 100a and 100b (not shown in FIGS. 17 and 18) are replaced from one another. In such a construction, when the viewer 300 moves from the stereoscopic viewing position of image to the pseudo-stereoscopic viewing position (FIG. 17), the images are replaced from one another as shown in FIG. 18. As a result, an image viewing region xe2x80x9cRxe2x80x9d of diamond shape can be placed at a position corresponding to the viewer""s right eye, and an image viewing region xe2x80x9cLxe2x80x9d of diamond shape can be placed at a position corresponding to the viewer""s left eye.
The conventional method as above mentioned requires, however, a means to switch images for left and right eyes. When a large sized display is used, the number of viewer is sometimes plural. In this case, one of the viewer moves and thus images for a left eye and for a right eye are switched. This causes a problem that the other viewers who are in stereoscopic position can not observe stereoscopic images.
The present invention is made in consideration of the above circumstances and it is an object of the invention to provide a stereoscopic display without using special eye-glasses which enable each viewer to observe a stereoscopic image without using a means to switch images for left and right eyes even when images are observed by a plurality of viewers.
To solve the problem, a stereoscopic display without using eye-glasses of the present invention comprises a first projector which projects an image for a left eye, a second projector which projects an image for a right eye, an image forming means which forms images for left and right eyes projected from the projectors onto a diffusing plate, a shutter means which includes a plurality of shutter regions disposed laterally which can switch between light transmission and light shading, and forms a narrow-width image light reaching region, of which width is less than that of the image forming region, in each image forming region on the diffusing plate, a light guide means which guides an image in a narrow-width image light reaching region for a left eye in the image forming region for a left eye to the left eye of the viewer and guides an image in a narrow-width image light reaching region for a right eye in the image forming region for a right eye to the right eye of the viewer, a shutter control means which controls light transmission and light shading of the shutter region on the basis of output results from a sensor which detects a viewer""s position.
In the above construction, each image is fractionized in the image forming region for a left eye and the image forming region for a right eye on the diffusing plate due to the placement of shutter means . That is, an image light region of narrow-width (a light emitting point) is formed in the narrow-width image light reaching region. The images in each narrow-width image light reaching region which are fractionized move respectively in response to the viewer""s position when being controlled light transmission and light shading of each shutter region by the shutter control means, resulting in realization of head tracking against the viewer. The more images in the narrow-width image light reaching region formed in each image forming region exist, the more viewers can observe a stereoscopic image.
A stereoscopic display without using eye-glasses of this invention comprises a left-eye system, a right-eye system, and a half mirror which guides an image for a left eye from the left-eye system and an image for a right eye from the right-eye system by transmitting an image light from either of the systems and reflecting an image light from the other system, further, the left-eye system is composed by a first projector which projects an image for a left eye, an image forming means which forms an image for the left eye projected from the projector onto the diffusing plate in predetermined width, a shutter means which includes a plurality of shutter regions disposed laterally which can switch between light transmission and light shading, and forms a narrow-width image light reaching region, of which width is less than that of the image forming region, in each image forming region on the diffusing plate, a light guide means which guides an image in a narrow-width image light reaching region in the image forming region to a left eye of a viewer, a shutter control means which controls light transmission and light shading of the shutter region on the basis of output results from a sensor which detects a viewer""s position, and the right-eye system is composed by a second projector which projects an image for a right eye, an image forming means which forms an image for the right eye projected from the projector onto the diffusing plate, a shutter means which includes a plurality of shutter regions disposed laterally which can switch between light transmission and light shading, and forms a narrow-width image light reaching region, of which width is less than that of the image forming region, in each image forming region on the diffusing plate, a light guide means which guides an image in a narrow-width image light reaching region for the right eye in the image forming region for a right eye to the right eye of a viewer, a shutter control means which controls light transmission and light shading of the shutter region on the basis of output results from a sensor which detects a viewer""s position.
In the above construction, the above head tracking can be achieved.
The shutter means may be arranged in front of projection lenses of the projectors and may include two or more than two shutter regions which can switch light transmission and light shading and are placed laterally in width less than that of the projection lens. The shutter means may be arranged on a light incident side or light emitting side of the diffusing plate and may include two or more than two shutter regions which can switch light transmission and light shading and are placed laterally in width less than that of the image forming region.
To solve the above-mentioned problem, a stereoscopic display without using eye-glasses of this invention comprises a first projector which projects an image for a left eye, a second projector which projects an image for a right eye, an image forming means which forms images for left and right eyes projected from the projectors onto a diffusing plate by overlapping an image forming region for a left eye and an image forming region for a right eye, a first shutter means which includes a plurality of shutter regions disposed laterally which can switch between light transmission and light shading, and forms a narrow-width image light reaching region, of which width is less than that of the image forming region, in each image forming region for a left eye on the diffusing plate, a second shutter means which includes a plurality of shutter regions disposed laterally which can switch between light transmission and light shading, and forms a narrow-width image light reaching region, of which width is less than that of the image forming region, in each image forming region for a right eye on the diffusing plate, a light guide means which collects images from narrow-width image light reaching regions in the image forming regions in a position spaced apart by a predetermined distance from the diffusing plate, and a width between the images is equal to or shorter than the interval between the viewer""s pupils, and a shutter control means which controls light transmission and light shading of the shutter regions of the first and second shutter means on the basis of output results from a sensor which detects a viewer""s position, wherein the shutter means controls the first and second shutter means so as that a narrow-width image light reaching region in an image forming region for a left eye and a narrow-width image light reaching region in an image forming region for a right eye do not share a same region on the diffusing plate.
In the above construction, image light regions of narrow-width (light emitting point) are formed in each narrow-width image light reaching region which is formed in image forming regions for left and right eyes on the diffusing plate by arranging the shutter means. The images in each narrow-width image light reaching region which are fractionized move respectively in response to the viewer""s position when being controlled light transmission and light shading of each shutter region by the shutter control means, resulting in realization of head tracking against the viewer. Also, the image forming region for a left eye and the image forming region for a right eye overlap and form on the diffusing plate. Therefore, it becomes easier to form many narrow-width image light reaching regions in each image forming region, since the size of a single image forming region is larger than that when the images are formed alternately. The more images in the narrow-width image light reaching region formed in each image forming region exist, the more viewers can observe a stereoscopic image.
The first and second shutter means may be arranged in front of projection lenses of the projectors and may include two or more than two shutter regions, which can switch light transmission and light shading and are placed laterally in width less than that of the projection lens. In this case, the first and second shutter means may be same size with regard to the whole area and can be arranged laterally to be spaced apart from each other by a length integer times as long as the length of the whole shutter region. In such a construction, a single image forming region of image forming regions for a left eye and for a right eye are formed on the diffusing plate and are formed on the same area. Consequently each image shifts by a length integer times of image forming regions. Therefore, a desired stereoscopic image can be observed when either of the image for a left eye or the image for a right eye, which are formed on the same single image forming region on the diffusing plate shifts to the opposite direction by a length integer times of image forming regions.
The first and second shutter means may be arranged at a stop of the projection lens of the projector and may include two or more than two shutter regions, which can switch light transmission and light shading and are placed laterally in width less than the diameter of the stop. In such a construction, regardless of shutter regions of a shutter means, an image light from the projector is projected evenly from the projection lens and an image is formed in a narrow-width image light reaching region in an image forming region on a diffusing plate in response to a light transmitting region of the shutter means without failure.
A stereoscopic display without using eye-glasses of this invention comprises a projector which projects an image for a left eye and an image for a right eye in sequence, an image forming means which forms images for left and right eyes projected from the projectors onto a diffusing plate, a shutter means which includes a plurality of shutter regions that can switch between light transmission and light shading, and forms a narrow-width image light reaching region, of which width is less than that of the image forming region, in each image forming region on the diffusing plate, a light guide means which collects images from narrow-width image light reaching regions in the image forming regions to a position spaced apart from the diffusing plate by a predetermined distance, and the width between the images is equal to or shorter than the interval between the viewer""s pupils, and a shutter control means which controls light transmission and light shading of the shutter region on the basis of output results from a sensor which detects a viewer""s position.
In the above construction, each image is fractionized in the image forming region for a left eye and the image forming region for a right eye on the diffusing plate due to the placement of shutter means . That is, an image light region of narrow-width (a light emitting point) is formed in the narrow-width image light reaching region. The images in each fractionaized narrow-width image light reaching region move respectively in response to the viewer""s position when being controlled light transmission and light shading of each shutter region by the shutter control means, resulting in realization of head tracking against the viewer. The more images in the narrow-width image light reaching region formed in each image forming region exist, the more viewers can observe a stereoscopic image.
The shutter means may be arranged in front of a projection lens of the projector and may include two or more than two shutter regions, which can switch light transmission and light shading and are placed laterally in width less than that of the projection lens.
The shutter means may be arranged at a stop of projection lens of the projector and may include two or more than two shutter regions, which can switch light transmission and light shading and are placed laterally in width less than the diameter of the stop. In such a construction, regardless of shutter regions of a shutter means, an image light from the projector is projected evenly and an image is formed in a narrow-width image light reaching region in an image forming region on a diffusing plate in response to a light transmitting region of the shutter means without failure.